Tail Held Erect: Stop
Tail Rippling: Move forward slowly/with care
Tail Held Erect and Sweeping Slowly from Side to Side: Retreat silently
Tail Pointing Low, Parallel to the Ground and Sweeping: Spread out
Tail Flattened: Get down
Tail Bobbing: Enemy sighted
Tail Hooked: Danger
Tail Pointed Sharply: Go that way
Tail Held Erect and Waving from Side to Side: Stay behind me
Tail Kinked over Back: Follow me
Tail Flicking over Back: Leave, but be careful
Tail Tip Facing Other Way - Attack
Stroking another cat's spine or shoulder with the tail is a sign of affection or sympathy. Stroking on the cheek has the same meaning.
Lashing their own tail usually happens in times of anger. However, this can also be a sign of excitement.
Wrapping their tail around another cat shows affection or the need to protect. Mother cats often wrap their tail around their kit(s). The tail can also be used to beckon another cat.
The tail can also show different emotions; a drooped tail, for instance, usually means the cat is sad.
When first starting to hunt, it is instinct to swish their tail, but in order to catch prey properly, the tail must be kept still.
Swishing their tail can mean that the cat is very excited and ecstatic. It can also be a sign of commencing an action or contemplating an important decision.
Lifting their tail up is a form of composure, just as we humans sit up to recompose ourselves.
The tail can be used to brush another cat away if they're not wanted. However, it can also be used for the opposite: to beckon a cat closer.
When a cat cares for another cat, he/she can smooth their fur with the brush of the tail.
A cat can whisk their tail when being conceited to show that they know everything.
Twitching their tail can be a sign that they are skeptical about something.
Crossly whipping their tail is a demonstration of anger.